Share Based Awards (Tables)

3 Months Ended

Mar. 31, 2018

Share Based Awards

Schedule of restricted stock unit activity

	Restricted Stock Units
		Weighted-
		Average
	Number of	Grant Date
	Shares	Fair Value
Unvested, December 31, 2017	12,906,030	$	4.72
Granted	3,653,521		4.64
Vested	(2,949,189)		4.89
Forfeitures	(1,593,415)		4.41
Unvested, March 31, 2018	12,016,947	$	4.69

Schedule of stock option activity under the 2008 Plan, 2014 Plan and the Inducement Plan

		Options Outstanding
						Weighted-
	Number of					Average	Aggregate
	Shares		Weighted-			Remaining	Intrinsic
	Available	Number of	Average		Contractual		Value
	for Issuance	Shares	Exercise Price			Term (Years)	(In thousands)
Balance—December 31, 2017	1,859,997	7,738,496	$	4.34		3.96	$	4,897
Authorized	4,860,197	—
Stock options granted	(150,000)	150,000		4.75
Issuance of shares under 2017 Bonus Plans	(1,974,771)	—
Shares withheld from net settlement of restricted stock units	752,564
Restricted stock units granted	(1,678,750)	—
Exercised	—	(378,398)		1.73
Stock options canceled	646,451	(646,451)		3.90
Restricted stock units canceled	1,593,415	—
Balance—March 31, 2018	5,909,103	6,863,647	$	4.53		4.01	$	7,922
Vested and exercisable—March 31, 2018		6,190,488	$	4.51		3.61	$	7,405
Vested and expected to vest(1)—March 31, 2018		6,756,612	$	4.53		3.94	$	7,834

(1) Options expected to vest reflect an estimated forfeiture rate.

Schedule of stock-based compensation expense recognized

	Three Months Ended
	March 31,
	2018		2017
Cost of revenue	$	1,382	$	701
Research and development		4,767		2,766
Sales and marketing		2,529		1,772
General and administrative		2,015		1,308
Total	$	10,693	$	6,547

Schedule of weighted-average assumptions to estimate fair value of stock options granted to employees

	Three Months Ended
	March 31,
	2018	2017
Expected dividend yield	—	—
Risk-free interest rate	2.7%	2.1%
Expected volatility	50%	41%
Expected life (in years)	6.1	6.1

Schedule of assumptions used to calculate the fair value of Employee Stock Purchase Plan awards

	Three Months Ended
	March 31,
	2018	2017
Expected dividend yield	—	—
Risk-free interest rate	2.0%	0.9%
Expected volatility	52%	34%
Expected life (in years)	1.3	1.3

Schedule of unrecognized stock-based compensation expense net of estimated forfeitures

	Unrecognized		Remaining
	Stock-based		Weighted-Average
	Compensation		Recognition
	Expense		Period
	(in millions)		(in years)
Stock options	$	1.0	2.6
Restricted stock units		41.8	2.7
ESPP		0.8	0.6
Total	$	43.6